Historical Context

Bromoil was introduced by E.J. Wall in 1907, building on the earlier oil pigment process. It became a favourite of Pictorialist photographers for its ability to transform ordinary silver gelatin prints into painterly, hand-manipulated images. The process enjoyed particular popularity through the 1930s before declining with modernism's preference for "straight" photography.

The process exploits the differential swelling of gelatin based on its hardening by silver—shadow areas (more silver, more hardening) accept oil-based ink while highlight areas (less hardening) repel ink when water-swollen.

Chemistry

Bleach Bath

Component	Amount
Copper sulphate	25 g
Potassium bromide	25 g
Potassium dichromate	2 g
Water	1 litre

Alternative Bleach (Dichromate-Free)

Component	Amount
Copper sulphate	50 g
Potassium bromide	50 g
Water	1 litre

This bleach is slower but avoids hexavalent chromium.

Procedure

Print Preparation

Make print: Start with a well-exposed silver gelatin print, slightly darker than normal. Fibre-based paper is essential—RC paper does not work.
Fix thoroughly: Double-fix in fresh fixer to ensure complete silver conversion.
Wash: Wash thoroughly (1 hour minimum) to remove all fixer.
Dry: Dry completely before bleaching.

Bleaching

Bleach: Immerse dried print in bleach bath until image disappears and paper is pure white (10-30 minutes depending on print density).
Wash: Wash for 30 minutes to remove all bleach.
Dry: Dry completely. At this stage the print can be stored indefinitely.

Inking

Soak: Soak bleached print in water for 20-30 minutes until gelatin is fully swollen.
Surface preparation: Blot surface water but keep print damp. The gelatin should be swollen but not pooling.
Apply ink: Using a stiff brush (hog bristle or badger), stipple lithographic ink onto the print. The hardened shadow areas accept ink; the swollen highlight areas repel it.
Build up: Work gradually, allowing the image to build through successive applications. This is the artistic heart of the process.
Dry: Allow to dry completely.

Inks

Use stiff lithographic inks:

Black: Charbonel or Graphic Chemical lithographic black
Brown: Burnt sienna, sepia, or custom mixtures
Any colour: Bromoil allows any ink colour or mixture

Thin ink slightly with linseed oil or Burnt Plate Oil if too stiff to work.

Brush Technique

Different brushes produce different effects:

Brush Type	Effect
Stippling	Classic bromoil texture
Sweeping	Directional marks
Dabbing	Varied texture
Multiple brushes	Combine techniques

The hand of the printer is visible in every bromoil—embrace this as a feature, not a flaw.

Troubleshooting

Problem	Likely Cause	Solution
Ink won't adhere	Paper too wet; insufficient hardening	Blot more; longer bleaching
Ink in highlights	Paper too dry; over-inked	More water; lighter touch
Uneven inking	Technique; paper quality	Practice; try different paper
Bleeding edges	Water under edges	Better blotting
Image lost in bleach	Over-bleaching; weak print	Monitor carefully; denser print

Safety

Chemical	Hazard	Precautions
Copper sulphate	Toxic if ingested; skin irritant	Gloves; standard precautions
Potassium bromide	Low toxicity	Standard precautions
Potassium dichromate	Carcinogenic (hexavalent chromium)	Gloves essential; excellent ventilation
Lithographic ink	Skin irritant; flammable solvents	Gloves; ventilation

Bromoil Transfer

A variation where the inked image is transferred to another surface:

Ink the bromoil as normal
While ink is wet, press face-down onto damp watercolour paper
Run through press or hand-burnish
Peel apart

This produces a reversed image with softer edges and different paper texture.

Bromoil

Image characteristics

Key chemicals